Bought my 2DS in April, and it's my only gaming system barring an old Dreamcast.
Total: 280 hours
1. SMT Devil Summoner: Soul Hackers - 42:50 (Beaten the main story, not interested in post game)
2. Super Mario 3D Land - 27:43 (Beaten every level but the very last)
3. Legend of Zelda: A Link Between Worlds - 22:36 (Single playthrough of normal mode)
4. Bravely Default - 21:56 (Only on chapter 2, my current RPG)
5. New Super Mario Bros. 2 - 18:58 (Just collected every coin, will not be touching the million coin challenge, selling in the B/S/T)
6. Resident Evil: Revelations - 17:56 (One normal playthrough, didn't put time in raid)
7. Kirby: Triple Deluxe - 15:45 (Beaten story mode, got bored with
. Sold!)
8. Pro Evolution Soccer 2013 3D - 14:44 (Two seasons into Become a Pro mode and I've scored only two goals so far.
9. Ace Combat: Assault Horizon Legacy - 10:59 (Beaten story mode on normal, now making my way through again on Ace mode)
10. Pokemon X - 9:07 (Came pre-installed on my 2DS. Gotten past the first gym but haven't touched it in months. Will return after playing other games.)
And a buttload of games in the 2-5 hour range. Haven't poured in hours into any single game like other posters here but I'm thoroughly enjoying my time with these games.